Uniflow gas engine



May 4, 1937. H. L. JOHNSON 2,079,571

UNIFLOW GAS ENGINE Filed April 13; 1956 2 Sheets-Sheet i May 4, 193 7.

H. L. JOHNSON UNIFL OW GAS ENGINE Filed April 15, 1936 2 Sheets-Sheet 2 v l a 19 J6 i 5 l r c 76 7% 435%; i

43 75 all 44 4 O 45 45 a 75 I x 44 LL Q Patented May 4, 1931 UNIFLOW GAS ENGINE Harry L. Johnson, Waukegan, 11]., assignor to Johnson Brothers Engineering Corporation, Waukegan, 111., a corporation of Indiana Application April 13, 1936, Serial No. 74,227

15 Claims.

This invention relates to a unifiow scavenging combustion engine. of the type in which the pistons of adjacent cylinders are movable in unison and the cylinders are connected at their heads so that they have a common combustion chamber and common igniting means and one of the cylinders having a fuel intake and the other connected cylinder and exhaust both uncovered by the movement of the pistons therein.

The parent of this application was filed May 14, 1934, Serial No. 725,462.

Important objects of this invention are the modification of this general type of uniflow motor to provide a two-cycle marine engine of the outboard motor type; to the incorporation of an improved fuel feeding arrangement for high and low speeds and in starting; and in controlling the admission and compression of a charge of air and gas to and in the crank case where it is initially compressed.

In carrying out this invention many other important objects and advantages are obtained, most of which will be pointed out in detail in the specification.

In the accompanying drawings illustrating a preferred embodiment of the invention,

Fig. 1 illustrates the inventionin section as applied tothe power head of an outboard motor, most of the motor driving and exhaust parts be ing omitted or shown only in part for clearness;

Fig. 2 is a transverse section of the engine shown in Fig. 1 with upper and-lower outboard parts partially shown in elevation;

Fig. 3 is a section taken on the line 3-3 of Fig. 1 showing the upper fuel admission to the crank case;

Fig. 4 is a section taken on the line 4-4 of Fig. 1 showing the lower fuel admission to the crank case;

Fig. 5 is a section taken on the line 5-5 of 'Fig. 2 showing the admission and exhaust ports;

Fig. 6 is a top or end view of the cylinders. with the cylinder head removed; and

Fig. 7 is ,a detail sectional view showing a fuel admission passage from the crank case to the fuel admission port.

In carrying out this invention as applied-to a two-cycle combustion engine of the type in which opposite pairs of cylinders are mounted one above the other and extending'transversely of the normal path or the back of the boat to which an outboard motor is applied, the arrangement is such that the fuel admission parts are located at the front side of the motor where they will be freely accessible for adjustment by a person in the back of the boat and the exhaust muiiler and discharge are located at the opposite side and to the rear of the motor.

In a two-cycle motor it is common to admit an explosive mixture of fuel and air to a closed crank case which is then admitted to the cylinders on the suction stroke of the piston therein so that when compressed the mixture will be exploded. In the present double cylinder connected type of engine the fuel mixture is admitted to one of the cylinders of each group and exhausted from the other as the ports in the cylinders are uncovered by the movement of the pistons therein. The important novel features of the invention are in the admission of the fuel mixture separately to the upper, lower and central portions of the crank case, in the control therefor, and in the valve mechanism which controls the admission of these separate explosive mixtures to the crank case.

With this constructionit is possible to provide better scavenging of the exhaust gases; smoother contour of cylinder heads; less waste of fuel out the exhaust port; better piston compressionseal; less clearance space above the pistons; better combustion chamber shape for rapid flame propagation; better timing of the ports; longer opening of the fuel intake port; and a component result of less fuel gas escaping from the exhaust port which results in more power and economy in the operation of the engine.

Referring now more particularly to the drawings, an engine of the two-cycle type is shown as applied in the power head of an outboard motor in which the adjacent parts only are shown in more or less conventional form. Extending below the power head is a drive shaft casing, I0 mounted in a swivel collar ll pivoted at l2 in a, support l3 engaged over the upper end of a boat transom I4 to which the clamping bracket is attached by a screw member l5. At the top of the power head is a magneto casing l6 having a manual control lever l1 and a starting plate I8. At the rear of the magneto is a fuel tank I9 below which is a muilier '20 with an exhaust tubecrank casing 22 the crank is provided with a cen- Itral valve portion 28 and upper and lower valve portions 29 and 30 of a diameter greater than the engine stroke produced by the crank pins 3| and the, connecting portions 32 which extend between the middle valve portion 28 and the upper and lower valve portions 29 and 30. The middle valve portion 28 and the crank shaft ends 23 and 25 constitute the bearings upon which the crank shaft is mounted and the valve members 29 and 30 fit closely in the casing to constitute valve admission ports ashereafter described.

Extending laterally from the crank casing as shown more clearly in Fig. 2, are cylinder blocks 33 and 34, each comprising an upper cylinder 'having admission ports 35 communicating with the crank case through transfer passages 35 and a lower cylinder having exhaust ports 31 communicating with an exhaust passage 38 which leads to the mufller 20. Covering each pair of adjacent cylinders is a cylinder head 39 spaced from the wall between the cylinders to provide a fuel passage 48 in which is located a spark plug 4| inclined upwardly therefrom and connected by a short conductor 42 with the magneto.

The cylinders and cylinder head are commonly provided with a water cooling jacket 43 with an inlet 44 and an outlet 45 which constitute no feature of this invention.

Connected to the front of the casing.22. as

shown more clearly in Fig. 1, is a fuel transfer and admission control device comprising a casing 45 having a central passage 41 controlled by a choke valve 48 mounted on a rotatable stem 49 operated by a hand lever 50 and communicating with a passage 5| in the crank casing which connects' .at intervals of its rotation with a. passage 52 in the central valve member 28 thereby admitting fuel directly to the crank case. This casing 45 also has an upwardly extending fuel passage 53 communicating with a passage 54 (see alsoFig. 3) with the upper end of the crank casing '22, and a lower passage communicating with a lower passage 55 (see also Fig. 4) at the bottom .of the crank casing 22. These two passages 53 and 55 have throttle valves 55 and 51 respectively rotatable therein and jointly controlled by short arms 58 connected thereto and to a common operating bar 59.

At the outer end of the passages 41, 53 and 55 is an air admission housing 50 attached to the casing 45 with a protecting hood 5| over the air admission opening thereof. For admitting fuel to the several passages there is a fuel admission opening 52 in the central passage 41, an opening 53 inthe upper passage 53, and an opening 54 in the lower passage 55, all receiving fuel from a fitting 55 connected to the fuel tank I9 by a pipe 55 and controlled by needle valve mechanism 51 although the central passage 52 need not be provided with an adjustable needle valve since it is intended to have a fixed capacity for low speed running and is controlled by the choke valve 48 .for starting and running.

To admit a fuel mixture at the top of the crank case the rotary valve member 29 is provided with a port, 58 and the top of the crank case has a recess 59 in communication with the top fuel passage 54 extending from substantially one quarter of thecircumference of the valve mem-v ber 29 so that the port 58 will admit a fuel mixture to the crank case while this port is traversing the opening. Likewise the bottom valve member 38 has a port 13 and the crank case has an opening ll extending approximately one quarter or ninety degrees about the lower va e 31"!- piston rod I5 to'its proper crank pin 3| and the opposite cylinders being slightly staggered as shown more clearly in Fig. 2, so that the piston rods are connected for a straight thrust upon their crank pins to transmit the maximum power of the engine.

The pistons 15 operate in unison so that the motor is inherently balanced, the pistons on opposite sides of the center acting oppositely and counteracting their vibrational effects. The pistons in each pair of cylinders also operate in unison and when they are at the'inner end of their stroke as. shown in Fig. 2, the fuel inlet ports 35 are open for the admission of fuel and the exhaust ports 31 are open for exhaust, the exhaust ports extending outwardly in the cylinders to a greater extent than the inlet ports so that the exhaust will be opened before the inlet and will be closed later, thereby allowing the inlet gases to force the burnt products of combustion outwardly in the exhaust as completely as possible. thereby scavenging these cylinders more thoroughly of the exhaust gases. The outward movement of the pistons in the cylinders creates a suction in the crank case which draws in fuel through the upper and lower rotary valves 29 and 30, and through the central valve 28 if the choke 48 is not closed, the continued movement of the valves then closes the rotary valves, the compressed charge is fired in the outer ends of the cylinders by the spark plugs 4| and as the pistons move inwardly they compress the fuel charge drawn into the crank case causing it to be forced under pressure from the crank case through the transverse passages "and ports 35 thereby completingthe' cycle of operations.

With this construction the fuel passes always from the upper cylinder through the passage 48 and downwardly to the lower cylinder, expelling the gas therefrom, thus causing this type of motor to be known as a uniflow scavenging motor or engine. In order to equalizethe pressure above and below the central valve member fer passage I4 or a number of such passages may be provided in the casing beyond the outside of the valve or the bearing therefor as shown more 'ity of valve entrances increases the efllciency of the entire valve as a unit by permitting a separate adjustment and control of the fuel admitted to the different portions of the crank case. A more uniform mixture of fuel can be obtained for variable engine speeds as the valves for the different entrances can vary the density of the fuel admitted at the different points. For example, the entry leading tothe top of the crank case may admit all or most of the fuel with the air and the entry at the bottom of the crank case may admit a small part of the fuel or'none at all with the air. If there is then a tendency'for the fuel to condense in the crank case and to which will'pick up the fuel from the bottom of the crank case and deliver it in a more thorough 28 a trans- 2 mixture to the upper cylinderswhich receive the fuel.

Having a number of fuel entrys. all but one entrance may be closed with the throttle valves and the one not throttled may be used for starting or for running the engine at low speed. This condition is represented by using the central passage 41 and the choke valve 48 for starting and running at slow speed, keeping the throttle valves 56 and 5'! closed. Using one entry for the. air maintains the air and fuel velocity in its admission to the crank case,'thereby resulting in more consistent performance with better atomization of fuel and air. less dropping of the fuel from the air, and keeping the fuel in a better state of suspension within the crank case. This construction therefore provides for a more consistent mixture of fuel and air in the combustion chamber; the maintenance of a more uniform mixture at all speeds; better lubrication of the engine due to more equal distribution of oil which is mixed with the fuel for a two-cycle engine of this type; easier starting of the motor; and a greater economy in operation for all of these reasons. The exhaust port being farther away from the fuel or intake port, the time interval of gas passage between the ports allows for larger port areas with better scavenging and more resultant power and economy of operation.

In this construction the entrance for air and.

fuel through the end valves is both radially and axially, resulting in a large opening for admitting a full 'flow of fuel therethrough for a maximum time and causing increased volumetric efflciency. By reference also to Fig. 5 it will be seen that the admission ports 35 extend through the wall of the upper cylinder of each pair throughout substantially the entire circumference, and the exhaust ports 31 open from the lower cylinder of each pair throughout substantially the entire circumference, resulting in a full flow and a quick admission of the fuel and providing a full exhaust opening therefor.

As shown more clearly in Fig. 2, the exhaust ports being longer than the inlet ports, or extending closer to the outer end of the cylinder, and the pistons moving together without lag of either one, the exhaust ports will be first opened and last closed; if the inlet and exhaust ports terminate at the same distance from the end of the cylinder, they will be opened and close simultaneously; and under the latter conditions. if desired, the lower piston may be given an angular lead on the crank shaft with respect to the other piston so that the exhaust ports may be opened in advance of the inlet ports, a matter of ten degrees or more, and of course they will be closed a corresponding amount sooner. This latter arrangement allows the two cylinders-to be charged more completely with a useful fuel mixture and reduces the amount of the useful charge which escapes from the exhaust port. Other variations of the timing and control of the inlet and exhaust ports may be made without departing from the spirit and scope of the invention.

I claim:

1. In an internal combustion engine havinga 2. In a combustion engine having a closed crank case and a crank rotatable therein, a valve member connected to the crank at each end of crank intermediate the ends of the crank case for."

admitting air and gas thereto.

3. A combustion engine having a closed crank case for fuel under compression. a crank rotatable therein having rotatable valve members at each end of thecrank case and intermediate the ends thereof for admitting air and gas thereto in timed relation to the movement of the crank.

4. A combustion engine comprising a closed crank case for compressed fuel. a crank rotatable therein having rotary valve members at the ends of the crank cases and intermediate the ends thereof, the end valve members having port openings therethruugh and the ends of the crank case having passages leading, to diametrically opposite sides of the crank case for admitting fuel to the crank case in timed relation as the valve members are rotated.

5. In a combustion engine having a closed crankcase for fuel compression, a crank rota-table therein having a rotary valve member intermediate the ends of .the crank case forming a and having valve members carried thereby at the ends of the crank case with ports therein for admitting air and gas to the crank case, and means in the crank case forming an equalizing passage between the compartments at opposite ends thereof and around the outside of the central bearing member.

'7. A combustion engine having a vertically disposed crank case, a crank shaft rotatable therein, upper and lower valve members carried by the crank shaft having ports therein for controlling the admission of air and gas at the top and bottom of the crank case, a central-bearing member also carried by the crank shaft dividing -the crank case into separate compartments,

combustion cylinders and transfer passages con-' necting the cylinders with the upper portion of the crank case for the passage of fuel therefrom,

and means in the crank case forming an equal izing passage around the central bearing member.

8. In a combustion engine having a vertical closed crank case, a crank shaft rotatable therein having upper and lower valve members at the ends of the crank case, and means forming fuel passages to,.the upper and lower .ends of the crank case and controlling the admission of fuel therefrom by the said' valve members, and a jet in each passage for the admission of fuel.

9. In a combustion engine having a closed vertical crank case, a vertical crank shaft, valve members carried at the upper, lower and intermediate the ends of the crank case, a plurality of separate passages leading from a common inlet to the upper, lower and intermediate portions of the crank case and the admission of fuel controlled by the corresponding valves.

10. A combustion engine having a vertical crank case, a crank shaft rotatable therein, upper, lower and intermediate rotary valve members carried by the crank shaft within he crank 30 "fiat head for each pair of cylinders. having a valve members carried in the crank case at the ends and intermediate the ends thereof, ports in each of the rotary valves, a housing providing separate passages from a common entry to the crank case controlled by each of the said valve members, the central passage having a separately controlled choke therein, the end passages having jointly controlled throttles therein, and controlled means for the admission of liquid fuel to each of the passages separately.

12. In a combustion engine having a closed crank case, a vertical crank shaft rotatable therein, valves carried by the crank shaft for controlling the admission of gas and air at the top and bottom of the crank case, a plurality of pairs of opposed double cylinders secured to the crank case and having pistons connected to the crank shaft and movable in unison in each opposite pair of cylinders, means forming a transfer passage for fuel from the crank case to the upper .cylinder of each pair, an exhaust connection with the lower cylinder of each pair and a common passage between the cylinders and a spark plug in the passage between the cylinders.

'13. A uniflow scavenging engine having a closed crank case and a vertical crank shaft mounted therein, valves for admitting air and fuel to the top, bottom and intermediate the top and bottom of the crank case, means for separately controlling the said admission means, and means for transferring the fuel mixture from the crank case to the combustion chambers of the engine.

14. A uniflow scavenging engine having an upright crank shaft and a closed crank case therefor, valves in the upper and lower ends of the crank case operated by the crank shaft, and valve recesses and corresponding crank case passages together providing combined radial and axial inlet ports at the ends of the crankcase which are controlled by the said valves therein.

15. In an internal combustion engine of the uniflow scavenging type having a vertical crank case and a crank shaft rotatable therein, opposite pairs of cylinders connected to the crank case, and each pair of cylinders having a flat head with a passage in the head between the cylinders of the pair, means to admit fuel from the crank case to the-upper cylinder and means to discharge exhaust gases from the other cylinder of each pair, a spark plug disposed at an angle in the head and inclined upwardly therefrom with its igniting element in the common passage between the cylinders, valve means for control means.

' HARRY L. JOHNSON. 

